You will not get an official answer.
The party line has always been that you shouldn't draw more than 16 mA from an individual GPIO or more than 50 mA from the GPIO as a whole.
The maximum output of the 3V3 rail is a separate issue. It is more than 50 mA on recent Pis (I have a feeling it may be 500 mA sustained but you would need to check the specs of the converter chip being used on the Pis you are using).
EDITED TO ADD
To the best of my knowledge, based on Adafruit information, the 3V3/1V8 converter (as I think used on A+, B+, Pi2B, Pi3B) can supply up to 1 amp shared between the 3V3 and 1V8 (internal) rails.